Hypertension is a disease at the highest incidence rate worldwide and domestically. It is suggested that the increase of oxidative stress in biological cardiovascular organs and tissues has a significant role in the progress of hypertension or related diseases such as arteriosclerosis, hypercardia and renal function impairment (Non-patent Document 1, Non-patent Document 2). It was observed in the past that the generation of active oxygen and the like increased during blood pressure elevation and during disorders of cardiovascular organs, such as cardiovascular tubes and renal system, following the increase. It is also suggested that such active oxygen and the like cause hypertensive organ function disorders.
Because hypertensive patients generally never feel sick, the patients frequently never visit doctors until organ impairment begins at the last stage, so that the patients lead their lives without any treatment of the disease. Therefore, hypertension is the main cause of the incidence rate and mortality of cardiovascular diseases in humans. A great number of hypertensive patients are sensitive to salt contents from the standpoint that highly salty diets increase blood pressure or that blood pressure already elevated is exacerbated.
It has been known recently that the administration of a pharmaceutical agent eliminating active oxygen to hypertensive model animals or to humans is effective for suppressing hypertensive organ disorders and additionally for suppressing blood pressure elevation. In salt-sensitive hypertensive model rats where blood pressure is elevated in a manner dependent on the salt intake, the efficacy of such agent eliminating active oxygen is prominently observed (Non-patent Document 3).    Non-patent Document 1: Curr Hypertens Rep 2000; 2: 98-105.    Non-patent Document 2: Curr Hypertens Rep 2002; 4: 160-166.    Non-patent Document 3: J Am Soc Nephrol 2004; 15: 306-315.